In a medical field, various tools are used in recent years. For example, endoscopes, ultrasonic echo probes, brain retractors, aspiration tubes, and other kinds of tools are used. Such a medical tool must be held for a patient at a proper position. For this, a holding arm apparatus using a parallel linkage is employed.
The holding arm apparatus of this type holds a medical tool at an end of an arm of the parallel linkage (including a belt driving mechanism) and has a counterweight at the other end of the arm. For example, Japanese Unexamined Patent Application Publications No. 2002-165804 and No. 2005-211667 disclose apparatuses capable of maintaining a weight balance with respect to a medical tool, setting the medical tool at a required position and angle, and fixing the state with clutches.